Worldwide, consumption of raw materials and especially coal is increasing. For underground coal mining there are necessary mine networks reaching higher and higher depths. Associated to mine networks, mine ventilation networks exist having vital role in ensuring optimal microclimate conditions. Presently, every field of industry is using the computers at every production stage. Mining or mineral industry is not an exception. Today, due the great extent of the underground networks and the amount of data involved, we are using computers in solving problems of planning and design, engineering and control of mine atmospheric environment. The solving of a complex ventilation network of a mine cannot be done manually, and usage of a specialized software and advanced IT equipment is a must. One of the most advanced specialized software is VENTSIM Visual Advanced, developed in Australia. The software has been used by the authors for modeling and solving of two complex ventilation networks related to Lupeni and Uricani Mines. The concrete result consists in the accurate solving of natural repartition of the air flows at the branch level, based on automatic calculation of their lengths. Another important advantage offered by the application consists in 3-D solid visualization, allowing user to obtain any technical detail, from any angle.
During the development of an underground explosion phenomenon, due to the energy of dynamic wave, important mechanical effects are registered both in the affected mine workings and in ventilation constructions (stoppings and seals, ventilation doors, regulators and air crossings). An explosion directly affects the ventilation network by modifying specific operational parameters of the main fans. This creates a different natural post event repartition of the air flows, at the branch level. In order to ensure safety conditions after the event, it is necessary to restore the ventilation network. This complex process is based on critical pathways, for whose identification were first established ventilation constructions in relation with their emergency level. This paper presents the process for restoring a mining ventilation network affected by an explosion, following the determination of critical pathways, through successive steps for restoring the ventilation in circuits affected by the wave front. For presenting these steps and for highlighting obtained results, a case study was conducted, based on a hypothetical, medium intensity explosion scenario, produced in the underground of Uricani coal mine, a mining unit in the Jiu Valley carboniferous basin, Romania, using 3D CANVENT specialized software for modeling, simulating and solving ventilation networks.
The simulation of different situations that may occur in the operation of the mine ventilation network is performed on its virtual model, developed and optimized using dedicated software. Depending on the chosen scenario, on the network model are applied a number of changes (addition of new ventilation workings, addition / removal of branches and nodes, changes in aerodynamic parameters: pressure, air flow driven by the fan etc.), the ultimate goals being: to assess how the new model obtained respond to anticipated requirements, diagnose of existing or potential problems, providing a quick feedback to the operator by making available all the data necessary for decision making process. The complexity of the simulation lies in the need to execute a number of operations due to changes of the network structure and symbolism carried out on the virtual model. This article aims to simplify this process through automation and efficiency using software subroutines, subroutines containing the entire chain of operations performed for each step of the simulation, in order to reduce the simulation time and the level of complexity required for understanding the phenomena that occur in the mine ventilation networks.
In the process of underground coal mining a complex network of vertical, horizontal and inclined mine workings with the purpose of extraction, transportation and evacuation to the surface are utilized. The mining workings are also being utilized for ventilation network system, which is also used for ensuring the oxygen supply necessary for workers, as well for diluting explosive gases and/or toxic substances and, ultimately, for exhausting the heat resulted from underground workings. For air flow pumping, special fans, of high capacity, located at the surface of the main ventilation stations are used. The fan operating mode depends on aerodynamic parameters and also on the structure of the ventilation network. Knowledge of specific local network parameters leads to the optimization of air flow distribution. The novelty presented in the paper consists in analysing and optimising the complex ventilation networks of Lonea mining unit, based on the depresiometric, flowmeters measurements and the status parameters specifics to each branch. Worldwide, in high developed mining countries, solving a complex ventilation networks it's being carried out with the help of specialized software such as VentSim, VentGraft, VentPri, 3D Canvent etc., through discontinuous operating at the mining unit quarter or to a distant location, where upon the results obtained are presented to the ventilation specialists. The complex ventilation network afferent to Lonea mining unit was rendered, fixed and optimised, up-to-date, using 3D Canvent software.
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